How do I fix the swelling of the wood I treated with mayonnaise?

sand it and then apply finish

Paper bag cloth iron.

1)Place paperbag on dresser. Place cloth over paper bag. place hot iron over cloth. Make sure it's not set on steam. The point is withdraw out the moisture

2) a blow dryer and paper bag.

3) Or piece of cardboard and a heavy heavy weight. let sit over night. If cardboard appears moist you are on the right track.

4) Heavy-duty vacuum with excellent suction has worked in the passed but not as well as the first method.

The iron method is great for spilled wax on carpet and other fabrics.

Good luck!!🍀

It almost sounds like the surface is a wood laminate. It may go down when it dries, but it may have damaged the laminate.

Try ironing the area over a piece of newspaper or even better, paper sack, that should absorb the oils and help the stain/raised area go back down.

Try the ironing suggestion after drys. If not will have to repair it and possible refinish.